Large files change randomly upon access

I have a weird case of errors. Single bytes of big binary files seem to change randomly but consistently.

For example I copy a large dump via scp (5 GB). And when I make sha256sum it is different then on source computer. I make a 2nd copy and its checksum is different then both previous.

It's not only about sending files though. I check svn with tools that check file integrity and the files also has invalid checksum. And it is consistent about which revisions are broken. So running the check again yield same failure.

I did a smartctl check and the tool doesn't report any problems. And problems occur both on nvme and hdd.